It could be anything. It could be pictures of things. But become an expert in something unexpected and unregarded. Develop a passion. Learn how to communicate that to other people without scaring them off. Find the other few people who share your interest. Learn how to be useful in that community.
I collect Hello Kitty everything, here is my collection, also to come my slip on shoe collection, similar to my chucks in my other blog.
I have also found fellow hello kitty liker's through flickr
My Vans: Pink ones, Checkered Ones, Pony ones...